1. Field of the Invention
This invention relates to micromachined arrayed thermal probe apparatus, systems for thermal scanning a sample in a contact mode and cantilevered reference probes for use therein.
2. Background Art
The following references relate to the present application and are referenced herein by their reference number:    [1] C. C. Williams et al., “Scanning Thermal Profiler,” APPL. PHYS. LETT., Vol. 49, pp. 157, 1986.    [2] H. M. Pollock et al., “Micro-Thermal Analysis: Techniques and Applications,” J. PHYS. D: APPL. PHYS., Vol. 34, pp. 23–53, 2001.    [3] S. C. Minne et al., “Automated Parallel High-Speed Atomic Force Microscopy,” APPL. PHYSICS LETTERS, Vol. 72, pp. 2340, 1998.    [4] P. Vettiger et al., “‘Millipede’—More Than One Thousand Tips for Future AFM Data Storage,” IBM J. OF RES. AND DEV., Vol. 44, pp. 323–340, 2000.    [5] T. Akiyama et al., “Integrated Atomic Force Microscopy Array Probe With Metal-Oxide-Semiconductor Field Effect Transistor Stress Sensor, Thermal Bimorph Actuator, and On-Chip Complementary Metal-Oxide-Semiconductor Electronics,” J. OF VACUUM SCIENCE AND TECHNOLOGY B: MICROELECTRONICS AND NANOMETER STRUCTURES, Vol. 18, pp. 2669–2675, 2000.    [6] D. W. Lee et al., “Microprobe Array With Electrical Interconnection for Thermal Imaging and Data Storage,” J. OF MICROELECTROMECH. SYS., Vol. 11, pp. 215–221, 2002.    [7] S. A. Miller et al.,. “Scaling Torsional Cantilevers for Scanning Probe Microscope Arrays: Theory and Experiment,” PROC. OF THE TRANSDUCERS 1997 WORKSHOP, 1997, Chicago, Ill., pp. 455–458.    [8] D. Lange et al., “Parallel Scanning AFM With On-Chip Circuitry in CMOS Technology, ” PROC. OF THE INTL. CONF. ON MEMS, 1999, Orlando, Fla., pp. 447–452.    [9] M. H. Li et al., “Applications of a Low Contact Force Polyimide Shank Bolometer Probe for Chemical and Biological Diagnostics,” SENSORS AND ACTUATORS A (PHYSICAL), Vol. 104, pp. 236–245, 2003.
First introduced in 1986 [1], scanning thermal microscopy (SThM) has found a unique place among the several techniques of high resolution scanning microscopy. It permits mapping of topography, temperature, thermal conductivity, thermal capacitance, and performing microcalorimetry with sub-100 nm spatial resolution [2]. The scanning probe has a thermal sensor (typically a bolometer) at a sharp tip located at the end of a cantilever. Scanning is best performed with the probe in contact with the sample to eliminate the high thermal resistance of an air gap, but this conventionally requires a mechanical feedback loop to prevent the probe from scratching the sample. As in atomic force microscopes, the contact force is sensed by measuring probe deflection with a reflected laser. The desire to increase throughput in scanning microscopy (both SThM and AFM) has prompted the design of arrays in which multiple probe tips scan in parallel [3–8]. With arrays, however, the problem of feedback becomes a difficult issue because parallel scanning requires each cantilever to have its own addressable feedback loop. Individual actuation of cantilevers has been explored, including piezoelectric films [3, 6] and thermal bimorphs [8]. While these approaches are effective for limited variations in topography, they do not easily accommodate samples with micro level topographical variation, such as integrated circuits or biological cells. Furthermore, all types of integrated actuators require additional fabrication steps, control circuitry, and electrical interconnect, thereby increasing manufacturing and calibration complexity.